Stability tested after Arunta AMCAP upgrade

May 20, 2019 – For those who go to sea there is nothing as critical as understanding the stability of the ship as it encounters all the forces that ocean and weather can bring to bear in combination.

Therefore, after more than a year out of the water as part of her Anzac Midlife Capability Assurance Program (AMCAP) upgrade, HMAS Arunta (II) has undertaken an inclining experiment at Henderson Shipyard, Western Australia to test stability.

An inclining experiment is a test performed on a ship to determine its stability, lightship weight and the coordinates of its center of gravity. The experiment is applied to newly constructed ships greater than 24m in length, and to ships altered in ways that could affect stability.

The weight of a ship can be readily determined by reading draughts and comparing with the known hydrostatic properties. The ‘metacentric height’ (GM), which dominates stability, can be estimated from the design, but an accurate value must be determined by an inclining experiment.

The experiment involves positioning the ship in a still body of water and applying weights in varying configurations throughout the ship and measuring the list of the ship for each configuration.

The experiment that was performed on Arunta is important as Arunta is the first of class to undergo the AMCAP upgrade and the data from the experiment will be used as a basis for updating the trim and stability handbook for all future AMCAP ships.

The upgrade, being implemented by the Warship Asset Management Agreement (WAMA), includes significant improvements to major platform systems, such as the communications center, and the replacement of the ship’s long range air search radar.

Arunta’s Marine Engineer Officer, Lieutenant Commander Leonard Woodman, said the inclining experiment is another important milestone for both Arunta and the Anzac Mid-Life Capability Assurance Program (AMCAP).

“The inclining experiment, while being a standard practice after a significant upgrade, has provided good data that will support all the ships that come after us on the AMCAP,” he said.

“The inclining experiment is a key component in getting the ship ready to sail later in the year, and marks a key milestone of the post-production process.”

The AMCAP aims to remediate obsolescence issues and upgrades ship systems, positioning the Anzac Class ships for sustainment and maintenance of its warfare systems capabilities.

The Warship Asset Management Agreement (WAMA) is an alliance consisting of the Commonwealth, BAE Systems Australia, Saab Australia and Naval Ship Management Australia. Arunta is the first ship to complete the AMCAP upgrade.

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